Induction coil



- May 25 1926. 1,586,082

R. A. GILBERT INDUCTION COIL Filed Feb. 26, 1925 Ina/anion a5 0 1 (/7. (iiieri,

Patentea May 25, 1926.

mars stares INDUCTION COIL.

Application filed February 26, 1825. Serial No. 11,716.

This invention relates to induction coils and aims to provide a novel and improved device of this class. The invention is particularly but not exclusively adapted for 5 use in ignition systems for explosive engines and will best be understood by a description of one selected embodiment thereof, reference being had to the accompanying drawings illustrating the same, wherein,

i Fig. 1 is a vertical longitudinal section of the induction coil;

Fig. 2, a cross-sectional view on the line 22 of Fig. 1, showing the end-caps of the winnings and field-plates assembled thereon;

l5 and Fig. 3, a cross-sectional view of the endcap on the line 33 of Fig.2.

Referring to the drawings illustrating one selected embodiment of my invention, the

20 housing contains the usual primary and secondary windings 11, 12 grouped about a magnetic core 13 and provided with suitable leads for connection with the induction circuit and the ignition circuit, respectively.

25 The core is of the usual type employed in an open magnetic circuit, comprising a bundle of soft iron wires.

The housing herein illustrated is cylindrical in form and constructed of suitable 30 non-conductive material, the upper end being closed by a removable insulation cover 14c in which are imbedded at opposite points in its side wall a pair of exposed terminals 15 for connection with opposite ends 16 of 15 the primary or low-tension winding 11, and

the bottom being closed by a metallic plate 17 fitted into the interior of the housing.

This bottom plate is peripherally provided with a depending annular flange 18 adapted to fit into the housing 10, the lower extremity of the flange being bent outward to form a suitable seat 19 for the support of the housing. It will be observed that this seat operates as a stop to limit the extent to which, the winding assembly may be inserted into the housing.

The secondary or high tension winding 12 is connected at one end 43 to a terminal 20 mounted on the outer face of the housing,

0 the opposite end 37 of the winding being connected to ground by any convenient means, as, for example, by contact with the bottom plate 17 The windings and core form a unitary asizi seinbly fitted at opposite ends into end-caps which suitably insulateand protect the windings, the ends of the core being each seated in a corresponding circular recess 22 provided centrally on the inner face of the end-caps. A bore 23 communicating with the recess 22 is provided centrally in each of the end-caps to receive one end of a tierod 24 which extends lengthwise centrally through and beyond each end of the core and holds the associated parts of the winding assembly, including the end-caps, in rigid relationship. The tie-rod constitutes a rigid supporting element on which the winding assembly is detachably secured to and within the housing, and for this purpose is preferably threaded at each of its extremities beyond the core and carries on its upper end a washer 25 and nut 27 to secure the upper end-cap against displacement, while the lower end carries a washer 26 and is preferably screwed into a threaded recess provided on the inner face of a metallic stud 28 secured to the bottom plate 17 and projected through a central opening therein into the interior of the housing 10. $0 Said stud is formed at its lower end with areduced threaded extension 29 adapted to receive a nutor other suitable locking meniber (not shown) for engagement with a support. The tie-rod 2a is extended at its 85 upper end beyond the nut 27 for projection into an interiorly threaded socket member 30 transversely imbedded centrally in the housing-cover 14:, which is thereby firmly held in detachable position on the housing. Said socket member is provided with a corn tral opening in its bottom to receive the up per extremity of the tie-rod which engages with a threaded locking member 31 seated in the lower end of the socket member. I also preferably provide a removable screw 32 in the exposed upper end of the socket member on the surface of the cover 14: for detachable connection with an independent support when necessary.

Mounted on the exposed ends of the core 13 and engaging the outer face of each of the end-caps 21, I provide field-plates 38 each consisting preferably of two or more soft iron laminae held firmly in their respec- 105 tive positions by the nut 27 and stud 28 and the intervening corresponding washers. each of these laminae contains a radial slot 34: all the slots being arranged in registering position, and also with oppositely ar- 110 ranged transverse openings 35 adapted to receive withrespect to the upper fieldq late 4 and Cal the upper ends ol the leads 16, which are suitably protected by an insulation covering 36, and with respect to the lower vField-plate, one of such openings is utilized to receive the lead 3. of the secondary winding. The end-caps 21 are also provided with suitable oppositely arranged transverse openings 38 adapted to reg' Jter with the openings in the field plates and to receive correspondingleads of the windings.

The radial slots Sal; of the end-p ates are employed to hreal: up the eddy currents induced therein by the licld flux and which have the effect of opposing the magnetic field or "lux ot' the core, thereby destroying the eliiciency of the induction coil. It is es sential, therefore, that these slots should all be arranged in registering position where a plurality of laminae are employed, to avoid the effect of eddy currents otherwise set up. It frequently occurs in the manufacture of devices of this class that unskilled labor is employed to assemble the parts of the coil and the work is done in such haste that the slots of the field-plates are not arranged in proper registering position. After completion and test, it is always costly and sometimes dillicult to ascertain just wherein the defect lies. To avoid these errors I provide on the outer face of each of the end-caps 21 an extension member 39 forming a key adapted to register with said slots 34L of the end-plates and to maintain them in the registering position. Said member 39 is preferably of such proportions that it will lit readily into said slots and extensively engage the margins thereof to prevent both a turning n'iovenie-nt and side play of the fieldplates. 1 also preferably provide on each of the end-plates an additional extension member of reduced dimensions forming a boss 4:0 disposed opposite the extension memher Bil. Said boss extends into a suitable transverse opening ll provided in the fieldplates and cooperates with the extension member 35) to facilitate correct assembly and to prevent rotative movement of the plates.

To further consolidate the lilies of the field tlux at their weakest point, intermediate the ends of the core and the correspondiug held-plates, 1 provide an open band ol'- magnetic metal su'rrounding-the windings intermediate the end-caps Said band has a tendency to attract and consolidate the diverging lines of force passing between opposite em'is of the core and is preferably constructed with a gap or opening therein forming disconnect 2d free ends, after the manner of the plates 83, for the purpose of preventing the formation of eddy currents. This band 1 preferably permanently secure to the inner wall of the housing 10 so as not to interfere with the introduction or removal of the winding assembly, the inner end of the terminal 20 being extended through a 1,5ee,os2

suitable opening in the band and thereafter spun or burred over to form a holding shoulder.

it is manifest that my device is operable in any position and may be. mounted in any location found convenient for the purpose and ait'ording a suitably conductive surface for ground connection.

lt will be understood that the present invention is not intended to be restricted to the particular embodiment herein shown and that obvious modifications may be made therein without departing from the principle of the invention.

1 claim as my invention:

1. in an induction-coil, in cou'ihinzit'on, a core, primary and secondary windings surrounding the core, caps enclosing the windings, and lan'iinated field plates arranged on at least one of the caps, said field plates each having a radial slot therein, and means provided on the corresponding cap for requirinc all of the field plates to be assembled with the slots in registering position.

In an induction-coil, in combination, a core, primary and secondary windings surrounding the core, caps enclosing the windinns, and field plates arranged on the caps, said field plates each having a radial slot therein, and a registering member provided on the cans and adapted to extend into said slots.

3. In an induction-coil, in combination, a core, primary and secomlary windings grouped. about the core, caps enclosing the windings, and lield plates arranged on the caps, said lield plates each having a radial slot therein and an opening through the plate opposite such slot, and registering members on the caps for extending into said slot and said opening respectively.

In an induction-coil, in combination, a core, primary and secondary windings surrounding the core, caps enclosing the ends of the windings, and field plates arranged on the caps each having a radial slot therein, and an extension member provided on the caps adapted to fit into said slots for arranging and maintaining the field plates in the operative position.

ii. In an iiuluctiou-coil. in combiuatnm, a core, primary and secondary windings grou iied about the core, caps enclosing the windings, field plates arranged on the caps each having a radial slot therein, a tie-rod for securing the foregoing parts in fixed relationship, and means provided on the caps and cooperating with the field plates for insuring the assembling of the lield plates with said slots all in registering position with respect to one another.

In testimony whereof, I have signed my name to this specification.

RALPH A. GILBERT. 

